Question I have created different presets with different delay time. However when I recall them they will use the delay corresponding to the last tapped tempo. Why

The short answer: The Nova delay presets allow to use the global tempo / delay or the saved delay when being recalled. You must set this parameter before storing the preset. Before storing the preset check the led on the preset button: If it is flashing it means that you are in preset mode, if it is steady it means that you are in global mode. If you want to change the mode hold the type button for a couple of seconds until the led status changes.
The slightly longer answer: The Nova delay allows to have individual delay time for each preset, but also allows shared delay time between presets. When a delay time is shared between presets it is called: "global tempo".You can choose exactly which presets you would like to be "preset tempo" or "global tempo". The reason why it looks like presets do not keep the programmed delay time, is very likely because you have some/all of your presets enabled to use "global tempo". If you would like to change some/all of your presets to "preset tempo" then:
  1. Go to each individuel preset one at the time and hold the "type" button. You should now see that the led in the "preset" button starts blinking.
  2. Hold the "preset" button to store this change. Now the preset is enabled to use "preset tempo" and Nova Delay will remember this until you change it back to "global tempo" by holding the "type" button.
Please note: The manual mode setting always uses "global tempo", which is nice if you would like to have the same tempo between two delay settings during a song. You can do this by toggling between "manual mode" and "preset mode" with a "global tempo" enabled preset.